1. Field of the Invention
This invention relates in general to magnetic transducers for reading information signals from a magnetic medium and, in particular, to an improved magnetoresistive read transducer assembly.
2. Description of the Prior Art
The prior art discloses a magnetic transducer referred to as a magnetoresistive (MR) sensor or head which has been shown to be capable of reading data from a magnetic surface at great linear densities. An MR sensor detects magnetic field signals through the resistance changes of a read element made from a magnetoresistive material as a function of the amount and direction of magnetic flux being sensed by the MR element.
The prior art also teaches that in order for an MR element to operate optimally, various bias fields should be provided. One bias field which is usually employed with MR elements is referred to in the art as the longitudinal bias field which extends parallel to the surface of the magnetic medium and parallel to the lengthwise direction of the MR element.
Commonly assigned U.S. Pat. No. 4,103,315 discloses the use of antiferomagnetic-ferromagnetic exchange coupling to produce a uniform longitudinal bias along the MR sensor. The exchange coupling occurs at the interface between an fcc (face-centered-cubic) FeMn antiferromagnetic layer and a NiFe ferromagnetic layer.
One of the problems encountered with the use of FeMn is the high corrosion rate exhibited by this material when exposed to certain environments. The high atmospheric corrosion rate and the loss of FeMn during processing of the transducer are indicative of the reactive nature of FeMn. The reactive nature of FeMn also causes severe restraints on the vacuum tooling and increases processing time because of the long cycle times required to insure an acceptable vacuum.